Carbon sorbent for removal of metal catalysts from pharmaceuticals
Inventors
Srinivas, Girish • Dietz, Steven
Assignees
Publication Number
US-11077421-B2
Publication Date
2021-08-03
Expiration Date
2037-03-24
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Abstract
The present invention relates to a carbon sorbent the can selectively remove platinum-group metals and other heavy metals such as tin without co-removing organic synthesis products including pharmaceutical intermediates and finished Active Pharmaceutical Ingredients (APIs). The carbon sorbents of the present invention are made from low-cost, high purity starting materials and the resulting carbon sorbents are also very pure. The carbon sorbents possess a combination of certain nitrogen and phosphorous groups combined with mesoporosity (2 to 50 nm diameter pores) that proves the high metal adsorption.
Core Innovation
The invention relates to a carbon sorbent designed for the selective removal of platinum-group metals and other heavy metals such as tin from organic synthesis products, including pharmaceutical intermediates and finished active pharmaceutical ingredients (APIs). These carbon sorbents are manufactured from low-cost, high purity starting materials, primarily carbohydrates like sucrose, glucose, fructose, corn syrups, and starches, resulting in a product that is both cost-effective and very pure.
The key innovation lies in the carbon sorbents possessing a unique combination of chemical and structural properties: a nitrogen content of at least 3 weight percent in the form of pyridine, pyridone, pyrrole, or N—P bonds; an oxygen content between 7 and 16 weight percent; a phosphorous content of at least 0.8 atom percent; a high BET surface area (between 200 and 1700 m²/g); and a mesopore volume of at least 0.05 cm³/g with pore diameters from 2 to 50 nm. These features provide a high affinity for metal adsorption while minimizing co-removal of valuable pharmaceuticals.
The problem addressed is the efficient removal of toxic platinum-group metals (e.g., palladium, platinum, ruthenium, iridium, rhodium) and other heavy metals such as tin, which are used as catalysts or reagents in pharmaceutical synthesis. Current sorbents can be costly, contain impurities, lack selectivity, or remove significant amounts of the API. The new regulations require residual metal concentrations in APIs to be extremely low, hence creating a need for a selective, pure, and economical sorbent. The present invention addresses the shortcomings of existing solutions by offering a high-purity carbon sorbent that achieves high metal removal without significant loss of valuable pharmaceutical compounds.
Claims Coverage
The independent claim introduces one primary inventive feature that defines the specific composition and functional requirements of the carbon sorbent.
Selective carbon sorbent for removal of metals from pharmaceutical products
The carbon sorbent is characterized by: - A nitrogen content of at least 3 weight percent, present as pyridine, pyridone, pyrrole, or N—P bonds. - An oxygen content between 7 and 16 weight percent. - A phosphorous content of at least 0.8 atom percent, determined by X-ray photoelectron spectroscopy. - A BET surface area ranging from 200 to 1700 square meters per gram. - A mesopore volume of at least 0.05 cubic centimeters per gram, with mesopores sized between 2 and 50 nanometers in diameter. - Demonstrated uptake of at least 83 percent of platinum-group metals (specifically palladium) from a solution containing 1.3 ppm platinum-group metal in an organic solvent with the API present at 1.0 grams per 0.5 grams sorbent; and less than 1 percent of the API is simultaneously adsorbed by the carbon sorbent. - A pH value not exceeding 3.1.
The inventive feature covers a carbon sorbent uniquely specified by its elemental composition, mesoporosity, metal removal efficiency, low pharmaceutical adsorption, and low pH, aimed at purifying pharmaceuticals by selective removal of metal contaminants.
Stated Advantages
The carbon sorbents are low-cost due to the use of inexpensive, high purity carbohydrate starting materials.
The resulting carbon sorbents are of very high purity and contain very little impurities, including extremely low levels of trace heavy metals, sodium, and potassium.
The carbon sorbents provide high chemical affinity and selectivity for platinum-group metals and tin, enabling the removal of these metals without significant adsorption of active pharmaceutical ingredients (APIs) or valuable pharmaceutical compounds.
The carbon sorbents possess large mesopores, which facilitate high metal adsorption capacity and efficient liquid diffusion, essential for capturing bulky metal coordination compounds.
The carbon sorbents are stable and maintain their performance even in highly acidic or basic conditions, avoiding degradation unlike some conventional materials.
Documented Applications
Removal of palladium, platinum-group metals, and tin from pharmaceutical reaction products, including pharmaceutical intermediates and finished APIs.
Purification of products resulting from Suzuki coupling reactions catalyzed by palladium catalysts.
Purification of products resulting from Stille coupling reactions involving palladium catalysts and tin reagents.
Removal of ruthenium from products obtained from metathesis reactions catalyzed by Grubb's first generation ruthenium catalyst.
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